A three-dimensional flower-like Cu-based composite and its low-temperature calcination derivatives for efficient oxygen evolution reaction
A novel Cu-based composite with unique three-dimensional(3D)nanoflower-like morphology and meso-porous structure(abbreviated as Cu-NF)was developed,using zeolitic imidazolate framework-67(ZIF-67)as precur-sor via facile Cu ion etching,followed by low-temperature calcination strategy.The mass ratio of Cu2+to ZIF-67 played a key role in morphology control.Additionally,low-temperature calcination changed the chemical compo-nents of the active sites and improved the porosity for mass transportation with the original morphology preserved.Sample Cu-NF-300,calcined at 300℃displayed the best oxygen evolution reaction(OER)performance among all the samples,with a small overpotential of 347 mV in 1.0 mol·L-1 KOH and a low Tafel slope of 93 mV·dec-1 for OER.Significant improvement in the electrochemical activity is attributed to the 3D superstructure and low-temperature calcination activation,which offer a simple synthetic strategy for the fabrication of Cu-based electrocat-alysts for OER.